The proposed investigation of the factors expected to contribute to the formation of lasting adhesive joints in general and of the adhesiveness and ageing of dental restorative materials in the environment of the oral cavity in particular, will be continued and as far as possible be completed. Our previous work concerned the mutual interaction, precipitation, and interpenetration of natural and synthetic polyelectrolytes (also as modified by binding of small ions), with special reference to cationically and anionically charged collagen and parent gelatin. We had postulated that adhesive bonds in an aqueous environment must rely on better than physical adsorption, yet must not contain too dense a system of covalent or strong ionic bonds in order to remain mechanically viable. Thus, an interfacial bonding system of interpenetrating reacting macromolecules was sought.---- This approach requires some specific underpinning by studies of the rates and extents of coprecipitation and of interpenetration of polyelectrolytes, andd of the rate and extent of ion binding on complexed polyelectrolytes, especially of Ca- and phosphate- ions. The work also included adsorption studies of polypeptides on mineral surfaces as a function of their conformations as determined by the solvent, and careful thermodynamics studies of the solvation of the peptide bond under a variety of solubility conditions. Major portions of this study are in the process of publication. An additional year is required for the final experimentation, evaluation of results, and the extrapolation towards application.